A golf cup has a height of about 6 inches and is set in the golf green so that the upper edge is about 1 inch below the surface of the green. The base of the cup has a bore and a ferrule on the end of the flagstick is inserted in the bore to support the flatstick in the cup. There is insufficient clearance between the flagstick and the wall of the cup to permit the ball to fall into the cup with the flagstick in place.
It is important that the ferrule on the bottom of the flagstick fit in the bore in a manner so as to keep the flagstick in a precise vertical attitude. A sloppy fit between the ferrule and the bore in the cup creates a leaning condition for the flagstick which can block the ball from going into the cup.
A further requirement is that the flagstick must be firmly held in place in the cup under high wind conditions, yet there must be sufficient clearance between the ferrule and the bore to prevent the pin from being jammed in the bore while providing the necessary sand and dirt clearance.